Looking for help

Helpmates are the kind of problems that most chessplayers avoid. The usual complaint is that 'it has nothing to do with normal chess', which is mainly true. But as with other sorts of exercise, the effort in solving such puzzles may help improve your overall thought process.
As a bit of a taste here is an interesting helpmate in 2 (sourced from Solving in Style by John Nunn). The convention for helpmates is that Black moves first and White delivers mate on their 2nd move (with Blacks help). However there is more this problem than finding one solution. Once you have found the first answer, replace the Black piece on a6 with a Rook, then a Bishop, Knight and finally a pawn. So rather than 1 puzzle, it is actually 5 puzzles in 1. See if you can come up with the 5 answers.